The keeping of slaves was not the issue that the spinners would have you believe. Right before the Civil War, Congress passed the Corbin Amendment, which would have forever institutionalized slavery in this country under the Constitutiuon as an olive branch to the south if they would but stay in the union. The south left anyway because they were having to pay almost all of the bills for the federal government. Between 80-85% of the costs of running the govenrment came from tarrifs collected from the southern states for the export of their raw materials. Had Lincoln not waged war to get them back, the federal government would have been bankrupt in under a year.
Lincoln famously is credited with saying that if freeing slaves or keeping slavery would preserve the union, ie the federal government, that is what he would do. Prettty much a statist. All of the fancy philosophy out the window when HIS job was on the line.